FDA grants priority review for expanded Vyvgart use in gMG
Argenx says treatment could be more widely available this year
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- FDA granted priority review for expanded use of Vyvgart in gMG.
- Vyvgart destroys disease-causing antibodies, showing benefits in trials.
- Expanded approval could make Vyvgart available to more patients by year-end.
The U.S. Food and Drug Administration (FDA) granted priority review to Argenx’s application seeking to expand the approval of Vyvgart (efgartigimod alfa-fcab) to adults with generalized myasthenia gravis (gMG) who test negative for anti-acetylcholine receptor (AChR) antibodies.
If the supplemental biologics license application is approved, the infusion treatment would become available to a broader population of patients, including those who test positive for antibodies targeting muscle-specific kinase or low-density lipoprotein receptor-related protein 4, as well as those who test negative for all three types of disease-causing antibodies.
The company said the treatment could be available to those patients by the end of the year. It expects a decision from the FDA by May 10.
“This development brings us closer to expanding the use of Vyvgart in a broad spectrum of patients with myasthenia gravis,” Luc Truyen, MD, PhD, chief medical officer of Argenx, said in a company press release. “We look forward to continuing our dialogue with the FDA as they review our application.”
Trials show promise for expanded use
In myasthenia gravis (MG), the immune system produces self-reactive antibodies that attack proteins necessary for nerve-muscle communication, leading to MG symptoms of muscle weakness and fatigue. In most cases, AChR proteins are the target of these immune attacks. Other cases can be more difficult to diagnose, and patients have fewer treatment options.
Vyvgart accelerates the destruction of disease-causing antibodies by blocking FcRn, a protein that normally prevents circulating antibodies from being destroyed. It is administered via weekly infusions into the bloodstream in four-week cycles.
The application for expanded use drew on data from the Phase 3 ADAPT SERON trial (NCT06298552), which tested Vyvgart versus a placebo in 119 adults with gMG who were anti-AChR antibody-negative.
The study met its main goal, with Vyvgart outperforming the placebo in its ability to improve scores on the MG Activities of Daily Living (MG-ADL), which evaluates the disease’s impact on daily activities, after four weeks. Patients treated with Vyvgart saw their MG-ADL scores improve by a mean of 3.35 points, a change considered clinically meaningful.
Improvements were also seen on the Quantitative MG scale, which measures muscle strength. These benefits were consistent across treatment cycles. Vyvgart was generally well tolerated, with no new safety concerns.
“With Vyvgart … we are proving the power of our approach: to redefine treatment paradigms through disciplined evidence generation and to redefine patient outcomes with medicines that are both more effective and more convenient,” Tim Van Hauwermeiren, CEO of Argenx, said in a press release outlining the company’s strategic priorities for the year.
Broader goals
“This same playbook will guide our future, as we aim to launch a portfolio of new medicines that could transform the lives of more than 50,000 patients across 10 indications,” Van Hauwermeiren said. In addition to expanding access to Vyvgart, the company aims to advance similar treatments and accelerate innovation, including testing empasiprubart as an experimental add-on to Vyvgart.
The company plans to launch an autoinjector in 2027 for use with the subcutaneous (under-the-skin) formulation of efgartigimod (marketed as Vyvgart Hytrulo in the U.S.), with the aim of giving patients more independence and flexibility. Vyvgart Hytrulo is approved for the same MG indication as Vyvgart and for chronic inflammatory demyelinating polyneuropathy (CIDP), another autoimmune disease.
Argenx is also testing empasiprubart, an experimental antibody therapy designed to inhibit C2, a protein of the complement system, a cascade of proteins that work together with the immune system to protect the body. When activated, C2 triggers the complement cascade, leading to inflammation. Empasiprubart is designed to reduce inflammation and tone down the body’s immune response, which can have therapeutic benefits for immune-mediated diseases like MG.
A Phase 2 clinical study, ADAPT FORWARD 1 (NCT07284420), is recruiting up to 70 adults with gMG who test positive for anti-AChR antibodies at three locations in the U.S. Its goal is to test empasiprubart’s safety and effectiveness as an add-on infusion to Vyvgart compared with Vyvgart alone. Patients will first receive Vyvgart in Part A of the study. If eligible, they may receive Vyvgart plus empasiprubart in Part B; if not, they will continue to Part C, in which they will only receive Vyvgart. The study will last up to 54 weeks (just over a year).
The company is also running Phase 3 clinical studies testing empasiprubart in multifocal motor neuropathy and CIDP, two diseases that affect the nerves.
“Looking at the year ahead, we will expand our FcRn franchise and report the first Phase 3 data for our next potential blockbuster medicine, with four registrational readouts across both efgartigimod and empasiprubart,” Van Hauwermeiren said.
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